The invention relates to a moulded case low voltage electrical circuit breaker having three stable positions respectively open O, closed F and tripped DD.
The advantages of moulded case circuit breakers of the kind mentioned are well known and this technique is used for higher and higher ratings. Currents of high intensity require large cross-section conducting parts which are voluminous and heavy. It is also indispensable that the contact pressure and speed of separation of these contacts be increased in order to limit the duration of the breaking arc. All these modifications result in a particularly cumbersome and bulky operating mechanism, which limits the possibilities of using the moulded case technique.
The first object of the present invention is to enable an operating mechanism with increased contact separation speed to be produced without a notable increase in the volume occupied by this mechanism. Another object of the invention is to enable a circuit breaker mechanism to be produced providing strong acceleration of the moving contact as soon as the contacts separate.
A further object of the invention is to achieve a high current moulded case circuit breaker whose case has a relatively small height and whose contact pressure can withstand high currents.